Snail baits

ABSTRACT

The invention relates to new slug and snail baits consisting of at least one magnesium salt, calcium salt and/or iron salt, lignosulphonate, finely divided cereal meal optional binders and optionally. one or more additives. The invention further relates to a process for the preparation of these slug and snail baits and to their use for controlling terrestrial slugs and snails.

The present invention relates to new slug and snail baits, to a processfor their preparation and to their use for controlling slugs and snails.

It has already been disclosed to control terrestrial slugs and snailswith the aid of baits which contain feedants and molluscicidal activecompounds, such as methiocarb, metaldehyde or metal chelates (cf. DE 3503 608A, DE 36 12 161A, WO 96-05 728A, WO 97-26 789A, WO 99-25 194A, WO99-39 576A and WO 00-11 948A). However, the efficacy of thesepreparations is not always satisfactory.

There have now been found new slug and snail bait consisting of

-   -   at least one magnesium salt, calcium salt and/or iron salt,    -   lignosulphonate,    -   finely divided cereal meal,    -   if appropriate binders and    -   if appropriate one or more additives.

It has furthermore been found that the new slug and snail baits can beprepared by

-   1) finely grinding a mixture of    -   at least one magnesium salt, calcium salt and/or iron salt,    -   lignosulphonate, and    -   if appropriate additives,-   2) treating the resulting premix with    -   finely divided cereal meal,    -   if appropriate binders and    -   if appropriate additives,-   3) stirring the resulting homogeneous mixture with such an amount of    water that a paste results,-   4) extruding and comminuting the paste and-   5) drying the product obtained.

Finally, it has been found that the new slug and snail baits are highlysuitable for controlling terrestrial slugs and snails.

Surprisingly, the bait according to the invention are markedly moreefficient in the control of slugs and snails than the constitutionallymost similar, prior-art preparations of the same purpose.

The slug and snail baits according to the invention are characterized bythe components listed.

The active component for controlling slugs and snails is in each case amixture of at least one magnesium salt, calcium salt and/or iron salt incombination with lignosulphonate.

Suitable as salts of the abovementioned metals are, preferably,sulphates, carbonates and phosphates. Examples which may be mentionedare magnesium sulphate, magnesium carbonate, calcium sulphate, calciumcarbonate, iron(II) sulphate, iron(III) sulphate, iron(II) hydrogensulphate, iron(III) hydrogen sulphate, iron(II) hydrogen phosphate,iron(III) hydrogen phosphate, iron(II) hydrogen carbonate, iron(II)phosphate, iron(III) phosphate, iron(II) carbonate and iron(III)carbonate. The salts can exist as the hydrates or in anhydrous form.

Suitable as lignosulphonates are the commercially available salts oflignosulphonic acid. Preferred are alkali metal salts of lignosulphonicacid, such as, for example, sodium lignosulphonate.

Cereal meals which can be present in the slug and snail baits accordingto the invention are commercially available meals such as wheat flour,rye flour, rice starch and the like. Durum flour and wheat flour arepreferred. The meal is present in finely particulate form, preferably inparticle sizes of less than 250μ.

Binders which can be present in the baits according to the invention areall customary adhesives which can be used for the preparation of suchproducts. Adhesives which are preferably suitable are modified starch,formaldehyde-releasing substances, optionally partially hydrolyzedpolyvinyl acetate and/or molasses.

Modified starch is to be understood as meaning, in the present case,commercially available products of this type. Cold-swelling cornstarchis preferred.

Formaldehyde-releasing substances which can be present are all customaryproducts which are suitable for releasing formaldehyde.Urea/formaldehyde condensates are preferred.

Polyvinyl acetates which can optionally be present inpartially-hydrolyzed form, are preferably the products known under thetrade names Mowilith® (Clariant) and Mowiol® (Clariant).

Molasses are understood as meaning, in the present case, conventionalsyrupy mother liquors arising during sugar raffination.

Suitable additives which may be present in the baits according to theinvention are, preferably, preservatives, colorants, slug and snailattractants, grinding adjuvants, additives, bittering substances,repellants for warm-blooded species and anticaking agents, and alsowater and further molluscidal active compounds.

Substances which are suitable as preservatives are all those substanceswhich are conventionally used for this purpose. Preservatives which maybe mentioned by preference are benzoyl derivatives such as benzaldehyde,p-hydroxyaldehyde, benzoic acid, methyl p-hydroxybenzoate,p-hydroxybenzoic acid, propyl esters and phenols such as p-nitrophenol,2-hydroxy-bisphenol and unsaturated carboxylic acids such as sorbic acidand its derivatives.

Substances which are suitable as colorants are all those substanceswhich are conventionally used for this purpose. Examples which may bementioned are inorganic pigments such as iron oxides, titanium dioxideand Prussian Blue, and inorganic dyestuffs such as anthraquinone, azoand metal phthalocyanin dyestuffs.

Substances which are suitable as slug and snail attractants are allthose substances which are conventionally used for this purpose.Examples which may be mentioned are plant extracts and theirderivatives, and products of animal origin.

Suitable additives are substances which are suitable for adjusting thepH value in the bait preparations. An example which may be mentioned iscitric acid.

Substances which are suitable as grinding auxiliaries are all thosesubstances which are conventionally used for this purpose. Exampleswhich may be mentioned are kaolins, clays, talc, chalk, quartz powderand highly disperse silica.

Repellants for warm-blooded species with a repellent effect on suchanimals, such as dogs and hedgehogs, are all those substances which areconventionally used for this purpose. An example which may be mentionedis vanillyl nonyl amide.

Substances which are suitable as bittering substances are all thosesubstances which are conventionally used for this purpose. An examplewhich may be mentioned is clenatonium benzoate.

Substances which are suitable as anticaking agents are all thosesubstances which are conventionally used for this purpose and whichprevent aggregation and caking. Examples which may be mentioned aremoisture-absorbing powders such as kieselguhr, pyrogenic silicas,tricalcium phosphate, calcium silicates, alumina, magnesium oxide,magnesium carbonate, zinc oxide, stearates and fatty amines.

Substances which are suitable as additional molluscicidal activecompounds are all those substances which are conventionally used forthis purpose. Examples which may be mentioned are methiocarb,metaldehyde and metal salts, if appropriate as a mixture with complexingagents, examples which may be mentioned being chelates ofethylenediaminetetraacetic acid and iron ions and/or copper ions.

The content of the individual components in the slug and snail baitsaccording to the invention can be varied within a certain range. Thus,

-   -   The magnesium salt, calcium salt and/or iron salt concentrations        are generally between 0.1 and 20% by weight, preferably between        0.2 and 15% by weight,    -   The lignosulphonate concentrations are generally between 0.5 and        20% by weight, preferably between 1.0% by weight and 15% by        weight,    -   The cereal meal concentrations are generally between 50 and 90%        by weight, preferably between 60 and 88% by weight,    -   The binder concentrations are generally between 2.0 and 20% by        weight, preferably between 3.0 and 15% by weight, and    -   The additive concentrations are generally between 0 and 5.0% by        weight, preferably between 0 and 3.0% by weight.

When carrying out the method according to the invention, it is preferredto employ those components which have already been mentioned aspreferred components in connection with the description of the slug andsnail baits according to the invention.

In practice, diluent which can be employed are inert organic solventsand/or water. Water is preferably employed.

The amounts of the individual components are chosen in such a way thatthe substances are present, in the slug and snail baits according to theinvention, in those weight ratios which have been mentioned above. Theamount of water or diluent is chosen in such a way that a paste isformed in step (3) of the process. The amount of water employed isgenerally between 25 and 35% by weight, preferably between 27 and 34% byweight, based on the remaining constituents. However, the water contentis markedly lower in the slug and snail baits according to theinvention, since the product, which is initially obtained moist in step(5) of the production process, is still to be dried. Virtually only theresidual moisture in the cereal meal remains.

When carrying out the process according to the invention, thetemperatures can be varied within a certain range.

-   -   Step (1) is generally carried out at temperatures of between        0° C. and 30° C., preferably at room temperature.    -   Step (2) is generally carried out at temperatures of between        0° C. and 30° C., preferably at room temperature.    -   Step (3) is generally carried out at temperatures of between        0° C. and 40° C., preferably at between 10° C. and 30° C.    -   Step (4) is generally carried out at temperatures of between        20° C. and 60° C., preferably at between 30° C. and 50° C.    -   Step (5) is generally carried out at temperatures of between        20° C. and 90° C., preferably at between 30° C. and 80° C.

Steps (1) to (3) and (5) of the process according to the invention aregenerally carried out under atmospheric pressure. However, it is alsopossible to carry out the drying process in step (5) under reducedpressure. Step (4) is generally carried out under elevated pressure,preferably under a pressure of between 30 and 100 bar.

When carrying out the process according to the invention, all theequipment conventionally employed for such processes can be used. Thus,conventional grinding apparatuses, for example air-jet mills, are usedfor comminuting the material in step (1).

Customary mixers, into which additional substances such as binders andwater can be placed during the mixing process, are suitable for themixing processes in steps (2) and (3). Those which can preferably beused are ploughshare mixers, paddle mixers and twin-screw extruders.

Apparatuses which can be used for the extrusion in step (4) are thoseconventionally used in the food industry, with the aid of which a pastecan be extruded through die plates and subsequently comminuted.

Equipment which can be used for drying the moist product in step (5) iscustomary equipment for removing moisture from particulate solids. In apreferred embodiment, a procedure is followed in which the moist productis first predried in a fluidized bed and subsequently dried to thedesired final moisture level in a separate apparatus.

Specifically, the process according to the invention is carried out insuch a way that,

-   -   in step (1),    -   at least one magnesium salt, calcium salt and/or iron salt is        treated as a mixture with lignosulphonate and        -   if appropriate as a mixture with one or more further            molluscidal active compounds and        -   if appropriate with additives such as, for example, grinding            auxiliaries, preservatives, colorants and the like, and the            resulting mixture is ground finely,    -   in step (2), the resulting premix is mixed with finely divided        cereal, binder and, if appropriate, additives, to give a        homogeneous product,    -   in step (3) such an amount of water is added, with mixing and        kneading, that a paste is formed,    -   in step (4), the paste is extruded under pressure and        comminuted, and    -   in step (5), the particulate material is initially predried and        then subjected to a final drying step and subsequently cooled to        room temperature.

When carrying out the process according to the invention, the size ofthe slug and snail baits can be varied within a certain range in themanner desired in each case. In general, the paste is comminuted in sucha way that pellets or extrudates are formed. The average diameter, andaverage length, of the particles is generally between 1 and 4 mm,preferably between 1.5 and 3 mm.

The slug and snail baits according to the invention are highly suitablefor controlling terrestrial slugs and snails in agriculture andhorticulture. The slugs and snails include all those terrestrial slugsand snails which are mostly found in agricultural and horticulturalcrops as proliphagous pests. Important pests of this type are slugs,such as Arion rufus (red slug), Arion ater and other Arionidae, Limaxspecies, furthermore field slugs such as Deroceras reticulatum andagreste from the Limacidae family, and species of the Milacidae family,and furthermore harmful snails, such as those of the genera Cepaea,Discus, Helicigona and Helicella.

When controlling slugs and snails, the application rate of the baitsaccording to the invention can be varied within a substantial range. Ingeneral, between 2 and 15 kg of slug and snail bait are used perhectare, preferably between 3 and 7 kg per hectare.

The slug and snail baits according to the invention can be applied bycustomary methods, such as, for example, by broadcasting and drilling.

The invention is illustrated by the examples which follow.

EXAMPLE 1

Preparation of Slug and Snail Bait According to the Invention

A mixture of 92 g of magnesium sulphate heptahydrate, 45 g of sodiumlignosulphonate,  5 g of p-nitrophenol,  9 g blue color pigment,  1 g ofdenatonium benzoate and  2 g of highly disperse silica

is ground finely at room temperature. In a mixer, the resulting premixis mixed, with stirring and at room temperature, with 2608 g of durumflour with a particle size of less than 250 μm,  75 g of cold-swellingcorn starch and  15 g of urea/formaldehyde condensate.

Thereafter, 210 g of liquid beet molasses are sprayed on at roomtemperature, while continuing stirring. The resulting mixture is treatedwith 735 g of water at room temperature and mixed and kneaded until ahomogeneous paste has formed. The paste is subsequently extruded at 40°C. and a pressure of 60 bar through a die-plate and the extrudate iscomminuted to give pieces 2 to 3 mm in length. The resulting material isinitially dried in a fluidized bed at temperatures of between 30° C. and80° C. and then in a separate dryer at temperatures of between 30° C.and 80° C. In this manner, 3000 g of slug and snail bait are obtained inthe form of pellets.

USE EXAMPLE A

Bare experimental plots with a size of in each case 1 m² are establishedin the open at a distance of at least 1 m from one another. Two Tagetespatula (marigolds) were planted in the middle of each plot. The entireexperimental area was severely infested with Arion and Deroceras slugspecies.

To control the slugs, the experimental plots were scattered uniformlywith the slug and snail bait pellets stated in each case at theapplication rate stated in each case.

The test was evaluated 6 days after the treatment. The feeding damage onthe Tagetes plants caused by slugs and snails determined, and theefficacy of the baits was calculated in %. An efficacy of 0% means thesame feeding damage as was observed in the untreated control, while anefficacy of 100% means that no feeding damage was observed.

The preparations used, the application rates and the test results can beseen from the table which follows. The numbers given for the efficacy isthe mean of three experiments. Active compound concentration Applicationrate Efficacy Bait preparation in % in g/m² in % Control: — — 0 Known:Fe PO₄* 0.37 5 70 Fe EDTA** 0.9 5 70 According to the invention: Ex. 1:MgSO₄/Na- 0.3 5 100 Lignosulphonate*The iron(III) phosphate was employed in the form of the slug and snailbait which is commercially available under the name Ferramol ®(Neudorff).**Fe EDTA stands for iron chelate of ethylenediaminetetraacetic acid.Baits based on this complex are disclosed in WO97/26789A

USE EXAMPLE B

-   Test slugs: Arion distinctus and Arion hortensis-   Test crop: lettuce-   Test method: field experiment; experimental site Bury St. Edmunds,    UK

The “MgSO₄/ligno”-containing bait formulations are scattered onto 9 m²plots at a rate of 5 g of formulation per m² with 3 replications. Thecomparison standard Ferramol was likewise applied at 5 g of product/m².The plots were planted with in each case 25 lettuce plants.

The test was evaluated 7 and 14 days after application by determiningthe feeding damage (% plants with feeding damage) on the test plants. Inaddition, any symptoms of phytotoxicity were also evaluated.

The efficacy of the test substance is 100% (Abbott method) when nofeeding damage has been observed, and 0% when the feeding damage is justas severe as in the control. Active Phytotoxicity compound % % symptomsconcentration activity activity 1-14 Bait preparation in g/m² 7 DAT 14DAT DAT Control (5.0) (60.0) — (% Plants with feeding damage) Known:Ferramol 0.1 RB 0.005 46.0 66.7 zero According to the invention:MgSO₄/Ligno 0.5 RB 0.015 80.0 77.8 zero MgSO₄/Ligno 1.5 RB 0.075 80.069.5 zero

USE EXAMPLE C

-   Test slugs: Arion distinctus and Arion hortensis-   Test crop: lettuce-   Test method: field experiment; experimental site Bury St. Edmunds,    UK

The “MgSO₄/ligno”-containing bait formulations are scattered onto 9 m²plots at a rate of 5 g of formulation per m² with 3 replications. Thecomparison standard Ferramol was likewise applied at 5 g of product/m².The plots were planted with in each case 25 lettuce plants.

The test was evaluated 7 and 14 days after application by determiningthe feeding damage (% plants with feeding damage) on the test plants. Inaddition, any symptoms of phytotoxicity were also evaluated.

The efficacy of the test substance is 100% (Abbott method) when nofeeding damage has been observed, and 0% when the feeding damage is justas severe as in the control. Active Phytotoxicity compound % % symptomsconcentration activity activity 1-14 Bait preparation in g/m² 7 DAT 14DAT DAT Control (5.0) (60.0) — (% Plants with feeding damage) Known:Ferramol 0.1 RB 0.005 81.7 85.7 zero According to the invention:MgSO₄/Ligno 0.5 RB 0.015 81.7 61.6 zero MgSO₄/Ligno 1.5 RB 0.075 75.387.3 zero

1-3. (canceled)
 4. A slug and snail bait consisting of (a) one or moremagnesium salts, calcium salts, and/or iron salts, (b) alignosulphonate, (c) a finely divided cereal meal, (d) optionally, oneor more binders, and (e) optionally, one or more additives.
 5. A processfor the preparation of a slug and snail bait according to claim 4comprising (1) finely grinding a mixture of one or more magnesium salts,calcium salts, and/or iron salts, a lignosulphonate, and optionally, oneor more additives, to form a premix, (2) treating the premix with afinely divided cereal meal, optionally, one or more binders, andoptionally, one or more additives, to form a homogeneous mixture, (3)stirring the homogeneous mixture with an amount of water that results ina paste, (4) extruding and comminuting the paste, and (5) drying theextruded and comminuted paste thereby obtained.
 6. A method ofcontrolling terrestrial slugs and/or snails comprising applying a slugand snail bait according to claim 4 to the slugs and/or snails or totheir habitat.